A vacuum is a space with the absence of (nearly) everything.
The definition of a vacuum starts with a vacuum cleaner which reduces the air pressure by around 20%. Regarding the outer space we are talking about higher-quality vacuums.
Ultra-high vacuum chambers, common in chemistry, physics, and engineering, operate below one trillionth (10−12) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm³.
Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average in intergalactic space.
In the aerospace context, a vacuum is a state of low pressure or no atmospheric pressure in a given space. It is a critical aspect of space travel and is essential for several aerospace applications.
Examples of the use of vacuum in aerospace include:
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Spacecraft propulsion: The vacuum is used in spacecraft propulsion systems, such as ion thrusters and Hall-effect thrusters. These engines expel ionized gases in a vacuum to produce thrust.
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Scientific experiments: Many scientific experiments are conducted in a vacuum to eliminate the effects of air resistance and other atmospheric factors. For instance, vacuum chambers are used to simulate the conditions of space on Earth for testing equipment and materials.
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Life support systems: In spacecraft, vacuum is used to remove waste gases and create a breathable atmosphere. In this case, the vacuum is created by a life support system that pumps out carbon dioxide and other waste gases and replaces them with breathable air.
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Satellite communication: Satellites orbiting the Earth operate in a vacuum, allowing them to communicate with ground stations without interference from the Earth's atmosphere.
Similar concepts related to vacuum in the aerospace context include:
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Low-pressure environment: In addition to vacuum, aerospace engineers and scientists often work with low-pressure environments, such as those found at high altitudes or in the upper atmosphere.
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Space simulation: Vacuum chambers and other facilities are used to simulate the conditions of space on Earth, allowing engineers and scientists to test equipment and materials before deploying them in space.
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Inert gases: Inert gases such as helium and argon are used in aerospace applications to create low-pressure environments or to purge systems of unwanted gases.
In conclusion, vacuum plays a crucial role in several aerospace applications, from spacecraft propulsion to life support systems. It allows for the creation of low-pressure environments, which is essential for space travel and scientific experiments. Other similar concepts in the aerospace context include low-pressure environments, space simulation, and the use of inert gases.